"Enough said! I see it at a glance! Thank you, Barbican. Why did not they make you a professor of astronomy? Your hint will save me a world of trouble."[C]
Aided by the Mappa Selenographica , the travellers could easily recognize the different portions of the Moon over which they were now moving. An occasional glance at our reduction of this map, given as a frontispiece, will enable the gentle reader to follow the travellers on the line in which they moved and to understand the remarks and observations in which they occasionally indulged.
"Where are we now?" asked Ardan.
"Over the northern shores of the Mare Nubium ," replied Barbican. "But we are still too far off to see with any certainty what they are like. What is the Mare itself? A sea, according to the early astronomers? a plain o
